Final answer:
Noble gases exist as individual atoms rather than as molecules due to their full electron shells, which negates the need for bonding. This behavior is contrasted with other gases that form molecules to achieve stability by filling their outer electron shells, and is further attributed to the weak London dispersion forces present within noble gases.
Step-by-step explanation:
Noble gases exist as monatomic gases, which means they exist as individual atoms rather than as molecules. They include helium, neon, and argon, and this particular behavior derives from the electronic configuration of these elements. Noble gases have full electron shells, which means they do not need to form bonds with other atoms to complete their outer electron shell.
The behavior can be contrasted with that of other nonmetal gases like hydrogen, nitrogen, oxygen, fluorine, and chlorine, which exist as the diatomic molecules H2, N2, O2, F2, and Cl2 respectively. These elements form diatomic molecules to attain stability by filling their outer electron shells.
Another pointer is the weak London dispersion forces present within noble gases. The boiling points and melting points of the noble gases are extremely low relative to those of other substances of comparable atomic or molecular masses. This is because only weak London dispersion forces are present, and these forces can hold the atoms together only when molecular motion is very slight, as it is at very low temperatures.
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